How air pollution delayed a surge in extreme rain | Grist

Source: How air pollution delayed a surge in extreme rain | Grist

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Like greenhouse gases, aerosols are produced by cars, factories, and power plants — but unlike greenhouse gases, they make the earth cooler rather than warmer. This is because aerosols reflect the sun’s rays, rather than trapping its heat like carbon. Some studies estimate that, without aerosol pollution, the world might have already warmed by another half a degree Celsius. 

This creates a tricky paradox, which renowned climate scientist James Hansen has called a “Faustian bargain.” If you remove aerosols from the air, you reduce the health impacts of pollution, saving thousands of people from lung and heart disease, but you might also make global warming worse. This powerful relationship has been on display over the past few years in the maritime shipping industry: As freight ships have stopped using dirty bunker fuel since 2020, they’ve also stopped emitting trails of sulfur dioxide, which has caused world temperatures to jump by an additional .05 degrees C.

Now, new research shows that the interaction between aerosols and greenhouse gases also has implications for flooding, which is one of the costliest climate disasters. A peer-reviewed paper published this week in Nature Communications finds that the presence of toxic aerosols in the atmosphere over the United States helped suppress the impacts of climate change on rainfall for decades, postponing a surge in rainfall and flood risk driven by climate change. The passage of clean air laws, which removed these aerosols from the atmosphere, ironically unleashed a trend of worsening floods